Local-global paradigm: auditory neurostimulation

Abstract

A major scientific challenge in the area of neuroscience is to detect some conscious processing in patients with disorders of consciousness. In this Final Degree Project has been designed a paradigm that evaluates cerebral responses to violations of temporal regularities that are either local in time or global across several seconds. The goal is being able to differentiate patients in a vegetative state from those in a minimally conscious or conscious state through Electro-Encephalography (EEG) signals. An EEG cap with 16 channels has been used to detect the Evoked Related Potentials (ERP) components in the response of the auditory stimulus. The sounds have been presented to some voluntaries through a Graphical Interface from MATLAB Simulink in where the signals have also been taken, amplified and recorded at real time. The auditory odd-ball paradigm consists in series of five sounds with some different sounds between them in order to induce a change in brain signals of the listener. These changes, called Evoked Related Potentials, have been isolated and observed to predict the future diagnosis of patients with disorders of consciousness. If people without the ability to interact with their environment present some peaks in their brain potential, it is possible that they may wake up soon. A Simulink model from MATLAB has been designed and programmed to make a way of communication between the biological signals of brain and the computer. Acquisition systems from g.tec medical engineering have also been used. Then, these signals have been processed to obtain the resulting graphics of voltage in function of time. Some voluntary people have been requested to do the experiment. It has been possible to register the brain signals from four healthy people and only one patient with brain disease has been presented. It is not possible to confirm that the presented system in this project can predict the response of patients with a disorder of consciousness according to the number of people used to test it. But a first approach of the pattern that would follow the brain signals in this type of patients can be stablished.